Flame resistant composition and method of treating acrylic containing textile fibers therewith and the resulting product



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Unite ING PRODUCT Julian J. Hirshfeld, Decatur, Ala., assiguor to Monsaiito Company, St. Louis, M0,, a corporation of Delaware No Drawing. Filed June 19, 1964, Ser. No. 376,555

9 Claims. (Cl. 117136) 2 ABSTRACT OF THE DISCLOSURE A new finish composition for improving flame re sistance of fibrous materials containing synthetic fibers comprised of a hydroxylamine salt alone and/or in combination with urea or a melamine resin, and a method of applying same Acrylonitrile containing polymers have been used as the basis for a wide variety of fibers and filaments useful in many textile applications. However, these otherwise excellent fibers suffer from a lack of flameiresistance which is an undesirable characteristic for many of their applications. Several ways have been proposed to 'iemedy this deficiency. Copolymerization of acrylonitrile with certain halogen containing monomers such as vinyl chloride or vinylidene chloride resulted in fibers having apprecia=ble flame resistance, but the product was inferior with respect to other end uses such as heat stability, dyeability, and physical properties. Halogen or phosphorus compounds when added to the spinning dope also result in fibers having significant flame resistance, but generally, these compounds interfere with the spinning of the fibers and have an adverse affect on physical or chemical properties of the fiber product.

One method to circumvent the above diffioulties is to apply a flame retardant to the fiber or fabric after it has been produced according to conventional techniques. Ammonium bromide when applied to the acrylonitrile fibers by an aqueous bath reduces the flammability of the fiber to some degree, but is not sufficiently effective for most applications.

Other chemical fibers are also highly flammable. Nylon when used alone is not flammable to a hazardous degree, for the nylon melts thereby having the tendency to extinguish the flame; however, when blended with a fiber which does not melt, the latter serves as a wick for the former thereby rendering the former highly flammable.

Accordingly, an object of this invention is to provide a fini h composition which may be applied to acrylonitrile containing fibers or fabric to impart appreciable flame resistance thereto without degrading theother properties of the fiber.

Another object of this application is to provide a composition of matter which may be applied to any synthetic fiber for the purpose of reducing the flammable characteristics thereof.

A further object of this invention is to provide a finish composition which may be applied to a blend of synthetic fibers and cotton fibers or fabrics to impart appreciable flame resistance thereto without degrading the other properties of the fiber.

A still further'object of this invention is to provide a method for applying the subject flame proofing composition to a fabric, fiber or the like.

Other objects and advantages of the invention will become apparent from the disclosure which follows.

3,383,240 Patented May 14, 1968 In general, the objects of the invention are accomplished by associating fibers or fabric which are at least partially comprised of synthetic filaments with an aqueous solution comprising a salt of hydroxylamine which may or may not be in combination with urea or a melamine resin. Two such salts of hydroxylamine which may'be used with excellent results are hydroxylamine sulfate and hydroxylamine phosphate. One melamine resin which may-be-used in combination therewith is Resloom M- which is manufactured by Monsanto Company, St. Loius, Mo. Resloom M-75 is hexamethylol-melamine having the formula III-(0112011);

This is set out in Neue Verfahren in der Technik der Chemischen Veredlung der Textilfaserr by Louis Diserens, volume 3, page 528, published 1957 by Birkhauser Verlag, Bassel, Stuttgart. The fibers or fabric, having been immersed in the aqueous solution, are then dried whereupon a deposit of flame retardant residue is left thereon.

Hydroxylamine and its salts are well known as a treatment for acrylic or other synthetic fibers which contain the CN end grouping as a means to increase the acid dyeability of these fibers, as described in US. Patent 3,083,070 to Schouteaen. In these fibers, 'the -CN groups are partially converted to basic -C(NH )=NOH groups by the hydroxylamine, thereby increasing the affinity of the fibers for acid dyes. It has now been discovered that the same reaction also serves to substantially in crease the flame resistance of the acrylonitrile fibers, and furthermore, that the hydroxylamine treatment similarly reduces the flammability of natural cotton fibers.

It hasalso been discovered that urea or melamine resins, which have little or no effect on the flammability of acrylic or cotton fibers when applied alone, display a significant synergistic action in combination with the hydroxylamine salts to further increase the flame retarding effect of the latter. 7

According to this invention, fabrics of cotton or acrylic fibers arepadded with an aqueous solution of hydroxylamine sulfate or hydroxylamine phosphate in combination with urea formaldehyde or melamine resin, and dried at about 220 F. to remove the water after which they may or may not be cured for approximately 10 minutes at about 300 F. The fabrics are then evaluated for hand, color, and flammability according to the.

AATCC Standard Test Method 33-1962, Flammability of Clothing Textiles. Tests have shown that this composition does not substantially alter the physical or chemical properties of the fiber, such as, strengthfcolor, heat stability or the like.

The urea formaldehyde resins contemplated herein are water soluble and are methylol urea resins consisting of monomethylol urea and dimethylol urea and mixtures thereof obtained from the reaction of one mole of urea with 1 to 2 moles of formaldehyde. 'I

The melamine resins contemplated herein are methylol melamine resins selected from the group consisting of tri-, tetr-a-, and pentamethylol melamine and alkylated methylol melamine derivatives thereof, hexamethylol meltau amine, and mixtures thereof which may be expressed by the formula R2 1%I-CH2OH N/ III HOHzC-NJJ\ /CIII-CH2OH 1hr \N Ra wherein :R R and R may be alike or different and are selected from the group consisting of H, CH C H and CH OH.

The following examples are cited to illustrate the invention. They are not intended to limit it in any way. Unless otherwise noted, all percentages as expressed in the examples indicate percentage by weight. The wet finish pickup or weight of finish solution applied to the fabric in all examples was equal to 80 percent of the weight of the fabric. Fabric hand was graded from 1.0 to 5.0, where 5.0 indicated the hand to be unchanged and decreasing numbers indicate increasing harshness. Burning time was measured in seconds from ignition until the sample was consumed. The notation OUT in the following examples denote the sample to be self-extinguishing.

EXAMPLE I Three swatches of Acrilan (a copolymer being comprised of acrylonitrile and vinyl acetate manufactured by Chemstrand Company, a division of Monsanto Company) awning fabric 2 by 6 inches were padded with an aqueous solution of 5 percent hydroxylamine sulfate (HAS), the weight of finish solution applied being equal to approximately 80 percent of the weight of the dry fabric. The swatches were dried at 200 F. and then cured for 10 minutes at 300 F. The treated fabrics were subjectively graded for change in hand and color and evaluated for flammability according to the standard AATCC test described above. An average of the data obtained is presented under Condition A in Table I. The test was repeated using higher concentrations of HAS (Cond. B-D) and also with four concentrations of urea formaldehyde ('UF) (Cond. E-H). A mixture of 5 percent HAS plus 5 percent urea was evaluated under Cond. I, and a second mixture of 10 percent HAS plus 5 percent urea was evaluated under Cond. I. An untreated control sample was included as Cond. K.

It is obvious from the above data that a 5 percent solution of HAS has little effect on the flammability of the acrylic sample, while at 10 percent and percent concentrations it is very effective. The application of urea at concentrations ranging from 5 percent to 20 percent has virtually no effect on the flammability of the sample. However, the synergistic action of the urea at the 5 percent level in combination with HAS at the 5 percent and 10 percent levels is quite evident in Co'nditions I and J, which may be compared to corresponding levels of HAS alone in Conditions A and B. The great advantage of the synergistic @QtiQQ Qt urea in o tion with the HAS is one of economics. The HAS is considerably more expensive than the urea so that a combination of 5 percent HAS/5 percent urea which gives flame protection equal to treatment with 10 percent HAS is far more economical. If even greater protection is desired, 10 percent HAS with 5 percent urea may be substituted for 15 percent HAS with nearly equivalent results.

EXAMPLE II The test procedure described in Example I was repeated using Resloom M- (a melamine resin produced by Monsanto Chemical Co., St. Louis, Mo.), as a substitute for urea formaldehyde. The solutions employed and the results of the evaluation are presented in Table II.

,It is obvious from the above data that the Resloom which imparts no flame resistance by itself, also displays a synergistic action in combination with the HAAS as did the urea in Example 1. Conditions A and B above show the samples treated with Resloom alone to have approximately the same burning time as the untreated control. Condition C utilizing 5 percent HAS with 5 percent Resloom had a burning time of 92 seconds, as com-- pared to 20 seconds for 5 percent HAS alone as shown in Table I, or an increase of nearly 500 percent. Condition D shows a similar although somewhat smaller advantage of a 10 percent HAS/5 percent Resloom mixture over a 10 percent HAS solution.

EXAMPL'E III Table III.

TABLE III Cond. No. Finish Composition Burning Time (Seconds) The above data shows that the HAS alone is a fairly effective flame retardant at the 5 percent level, and is completely effective at the 10 and 20 percent levels. The combination of urea formaldehyde with the HAS has no apparent effect "at the 5 percent level, but the 10 percent urea/ 10 percent HAS combination is about 2.5 times as effective as 10 percent HAS alone.

5 EXAMPLE IV The evaluation described in Example 111 was repeated except that the treated fabric swatches were not cured at 300 F. The results of the evaluation are given in Table IV TABLE IV Cond. N 0. Finish Composition Burning Time It is evident from comparison of Tables III and IV that the curing step has no appreciable effect on the effectiveness of the treatment. However, it was noted that 20 the; physical strength of some treated specimens was degraded by the curing step and it is therefore desirable to dry the samples only and omit curing.

EXAMPLE V A solution of 10 percent hydroxylamine phosphate and 10 percent urea was applied to swatches of Acrilan and cotton fabrics. The fabrics were dried at 220 F., cured at 300 F., and evaluated for flammability by the standard AATCC test. The Acrilan fabrics burned an average of 6 seconds before going out. The cotton fabrics would not ignite.

Many modifications of the above will be obvious to those skilled in the art without a departure from the inventive concept.

I claim:

1. A composition suitable for imparting flame resistance to a hydrophobic shaped structure comprising an aqueous mixture consisting essentially of above about 5 percent based on the bath of a hydroxylamine salt and above about 5 percent based on the bath of a member selected from the group consisting of urea formaldehyde and a melamine resin 2. A composition according to claim 1 wherein the aqueous mixture consists essentially of between about 5 and about 25 percent based on the bath of a hydroxylamine salt, and between about 5 and about 20 percent based on the bath of a member selected from the group consisting of urea formaldehyde and a melamine resin.

3., A composition according to claim 1 wherein the hydroxylamine salt is selected. from the group consisting of hydroxylamine sulfate and hydroxylamine phosphate.

4. A flame resistant article composed of a fabric being at least partially comprised of synthetic fibers which have been treated with an aqueous mixture containing above about 5 percent based on the bath of a hydroxylamine salt and above about 5 percent based on the bath of a member selected from the group consisting of urea formaldehyde and a melamine resin.

5. An article according to claim 4 wherein the aqueohs mixture contains between about 5 and about 25 percent based on the bath of hydroxylamine salt, and between about 5 and about 20 percent based on the bath of a member selected from the group consisting of urea formaldehyde and a melamine resin.

6. An article according to claim 4 wherein the hydroxylamine salt is selected from the group consisting of hydroxylamine sulfate and hydroxylamine phosphate.

7. A method of rendering a fabric, being at least partially comprised of synthetic fibers, flame resist-ant comprising treating the fabric with an aqueous mixture containing above about 5 percent based on the bath of a hydroxylamine salt and above about 5 percent based on the bath of a member selected from the group consisting of urea formaldehyde and a melamine resin, and drying the fabric at an elevated temperature.

8. A method according to claim 7 wherein the aqueous mixture contains between about 5 and about 25 percent based on the bath of a hydroxylamine salt and between about 5 and about 20 percent based on the bath of a member selected from the group consisting of urea formaldehyde and a melamine resin.

9. A method according to claim 7 wherein the hydroxylamine salt is selected from the group consisting of v hydroxylamine sulfate and hydroxylamine phosphate.

References Cited UNITED STATES PATENTS 2,032,605 3/1936 Whitehead -I 117-136 2,953,480 9/1960 Burnell w 117-137 3,017,292 1/1962 Mosher 117-137 3,083,070 3/1963 Schouteden aaaaaaaaa 8115.5

WILLIAM D. MARTIN. Primary Examiner.

MURRAY KATZ, Examiner.

T. G. DAVIS, Assistant Examiner. 

